introduction.sgml

H.323网守实现

<sect>Introduction
<p>
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<sect1>About
<p>
<bf>
<url url="http://www.gnugk.org/" name="OpenH323 Gatekeeper - The GNU Gatekeeper">
</bf>
is an open-source project that implements an H.323 gatekeeper.
A gatekeeper provides call control services to the H.323 endpoints.
It is an integral part of most usefull internet telephony
installations that are based on the H.323 standard.

According to Recommendation H.323, a gatekeeper shall provide the
following services:
<itemize>
<item>Address Translation
<item>Admissions Control
<item>Bandwidth Control
<item>Zone Management
<item>Call Control Signaling
<item>Call Authorization
<item>Bandwidth Management
<item>Call Management
</itemize>

The GNU Gatekeeper implements most of these functions
based on the
<url url="http://sourceforge.net/projects/openh323" name="OpenH323">
protocol stack.

Recommendation H.323 is an international standard published by the
<url url="http://www.itu.int/" name="ITU">.
It is a communications standard for audio, video, and data over the Internet.
See also Paul Jones'
<url url="http://www.packetizer.com/voip/h323/papers/primer" name="A Primer on the H.323 Series Standard">.

For a detailed description of what a gatekeeper does, see
<url url="http://www.iec.org/online/tutorials/h323/topic06.html" name="here">.

<sect1>Copyright
<p>
It is covered by the
<htmlurl url="http://www.gnu.org/licenses/gpl.html" name="GNU General Public License"> (GNU GPL).
In addition to that, we explicitely grant
the right to link this code to the OpenH323 and OpenSSL library.

Generally speaking, the GNU GPL allows you to copy, distribute, resell or modify
the softwares, but it requires that all derived works must be published
under GNU GPL also.
That means that you must publish full source for all extensions to
the gatekeeper and for all programs you include the gatekeeper into.
See the file COPYING for details.

If that's not what you want, you must interface to the gatekeeper through
the status port and communicate via TCP with it.
That way you only have to integrate the basic funtionality into
the gatekeeper (and provide source for that) and can keep other parts
of your application private.

<sect1>Name
<p>
The formal name of this project is
<em>OpenH323 Gatekeeper - The GNU Gatekeeper</em>,
short <em/GnuGk/.
Please don't confuse it with other gatekeeper projects.

There are several open-source gatekeeper projects based on the OpenH323 protocol stack.
<itemize>
<item><url url="http://opengatekeeper.sourceforge.net/" name="OpenGatekeeper">
<quote>A gatekeeper available under MPL. The project has been inactive for a period of time now.</quote>
<item><url url="http://sourceforge.net/projects/openh323" name="OpenGK">
<quote>Only in a very primary grades.</quote>
<item><url url="http://www.gnugk.org/" name="OpenH323 Gatekeeper - The GNU Gatekeeper">
<quote>This one, also called GnuGk.</quote>
</itemize>

To have different gatekeepers with very similar names is really
confusing for most users.
Since our "OpenH323 Gatekeeper" was the first on the scene,
it is not our fault that others have chosen similar names.
But to make the destinction a little more clear without confusing
people even more, we have decided to give the project a
subtitle "OpenH323 Gatekeeper - The GNU Gatekeeper" and start
using <tt/gnugk/ as name for executables.

<sect1>Features
<p>
The version 2.2.3 contains the following new features and bugfixes:

<itemize>
<item>
New <tt/[RewriteCLI]/ options to control CLIR features precisely.

<item>
New CLIR/CLIP (Calling Line Identification Restriction/Presentation) features
in the <tt/[RewriteCLI]/ module. Ability to hide CLI (enable CLIR/CLIP) per endpoint.

<item>
New <tt/[RoutedMode] SocketCleanupTimeout/ config variable. More reliable
socket management and better network error reporting.

<item>
The <tt/RewriteCLI/ module rewrites outbound rules correctly for random
numbers separated by commans.

<item>
Broadcast request are handled correctly in the LARGE_FDSET mode.

<item>
New ENUM routing policy from Simon Horne.

<item>
NetMeeting compatibility problems fixed.

<item>
A new <tt/[RasSrv::RRQFeatures] IRQPollCount/ config variable. Default number
of "poll" IRQ messages changed from 2 to 1 to allow faster endpoint unregistration.

<item>
Tunnelled H.245 messages were not processed correctly (were ignored).

<item>
<ref id="fileipauth" name="[FileIPAuth]"> module moved from the contrib
section into the main branch.

</itemize>

<p>
The version 2.2.2 contains the following new features and bugfixes:

<itemize>
<item>
New CLI rewrite types - prefix replacement (*=) and identity match (~=).

<item>
A new <tt/TranslateFacility/ config variable to enable Facility message conversion
between H.323v4 and previous versions of the protocol.

<item>
<tt/SignalTimeout/, <tt/AlertingTimeout/ and %t, %p, %{ring-time}, %{alerting-time}
accounting variables ported from 2.0 branch. <tt/ConnectTimeout/ config
variable replaced with <tt/SignalTimeout/ and <tt/AlertingTimeout/.

<item>
A new <tt/%r/ accounting variable to provide infomation about who
was the one that disconnected a call.

<item>
A new, generic <ref id="sqlauth" name="SQLAuth"> module for RRQ, ARQ, LRQ
and Setup authentication and authorization.

<item>
New --core command line argument to enable core dump generation for Unix.

<item>
A new <tt/Vendor/ config variable for <ref id="endpoint" name="[Endpoint]">
section to provide vendor specific extensions when registering with a parent gatekeeper.

<item>
LRQ nonStandardData field was not included for CiscoGK neighbors.

<item>
New <ref id="clirewrite" name="[RewriteCLI]"> config section
that allows arbitrary rewritting of ANI/CLI numbers.

<item>
New <ref id="numberanalysis" name="numberanalysis"> routing policy.

<item>
New FileIPAuth module in the contrib/ipauth directory.

<item>
Call accounting updates/call disconnect handling is now more robust
and does not lock the whole call table and (effectively) the gatekeeper
for long time periods.

<item>
Do not support mutiple rewrite targets, as this feature does not work well
if rewrite is performed more than once.

<item>
The gatekeeper could crash if the connection was closed before
the welcome message has been sent to the client.

<item>
Different Username was reported during Setup auth
and acct step, if no sourceAddress has been present for an unregistered call.

<item>
More missing config reload locks added to allow seamless config reload.

<item>
A default value for the config variable <tt/ForwardOnFacility/ changed to <tt/0/.

<item>
Ability to encrypt all passwords in the config. A new <tt/EncryptAllPasswords/
config variable, <tt/KeyFilled/ config variable usage extended.

<item>
Ability to read config settings from an SQL database ported from 2.0 branch.
Read <ref id="sqlconf" name="[SQLConfig]"> for more details.

<item>
Framed-IP-Address could not be determined for unregistered calls with
no Setup-UUIE.sourceCallSignalAddress field, causing authentication to fail.

<item>
Provide proper handling of aliases of type partyNumber
(e164Number or privateNumber).

<item>
A fix for RTP/Q931/H245/T120PortRange to correct a bug with port range 
wraparound if the last port is 65535. This caused a next port to be set 
to 0 and any subsequent port allocation to fail.

<item>
Dynamic allocation of RTP ports did not work, use a fixed port range 
1024-65535 as a default for the <tt/RTPPortRange/ config variable.

<item>
Obsolete auth modules MySQLAliasAuth and MySQLPasswordAuth are now removed.

<item>
SQL modules accept only one database host in the <tt/Host/ parameter.
</itemize>

<p>
The version 2.2.1 contains the following new features and bugfixes:

<itemize>
<item>
Enchanced prefix matching for routing policies. A dot (<tt/./) matches any digit.

<item>
Enchanced prefix matching for neighbors. A dot (<tt/./) matches any digit,
<tt/!/ at the beginning disables the prefix.

<item>
A missing lock during config reload caused the gatekeeper to crash.

<item>
More reliable port number selection for Q.931, H.245, T.120 and RTP
port ranges (earlier, a config reload could cause many calls to fail
because of unability to allocate a new socket).

<item>
Default value for RTPPortRange is now to let the OS select a port number.

<item>
More flexible rewrite rules (both global and per-gw) with new '.' and '%'
wildcard characters.

<item>
Enchanced prefix matching for gateways. A dot (<tt/./) matches any digit,
<tt/!/ at the beginning disables the prefix.

<item>
Insert missing Calling-Party-Number-IE/Display-IE if corresponing